Study of the pharmacokinetics of the antiarrhythmic drug sotalol in pediatric patients age newborn to 12 years. Sotalol has been widely used in pediatrics for rhythm control, but its pharmacokinetics has not been studied. The study will be a multi-center, open-label, one period, single dose pharmacokinetic study. The study will collect pharmacokinetic information from pediatric patients of different age groups after a single dose of sotalol solution. The study is to support the derivation of an appropriate dosage regimen for pediatric use of sotalol.